Shape memory alloy rearview mirror

ABSTRACT

A rearview mirror assembly having a pivot structure and first and second pairs of helical structures consisting of shape memory alloy wires which serve to adjust the position of the mirror. The wires may be individually heated by conducting an electrical current to effect the contracted memory position. When the current is switched off, a wire cools and can easily be stretched to mechanically transform the wire to a martensitic phase.

This appln is a 371 of PCT/US99/24042 filed Oct. 22, 1999, which claimsbenefit of Provisional No. 60/105,434 filed Oct. 23, 1998.

FIELD OF THE INVENTION

This invention relates to a power operated rearview mirror assembly fora motor vehicle.

DESCRIPTION OF THE PRIOR ART

Motor vehicles include rearview mirror assemblies mounted externally ona vehicle on one or both front doors to help the driver see rearwardlyof the vehicle. These rearview mirror assemblies typically have anadjustable mirror portion mounted therein that can be remotelycontrolled to be repositioned to accommodate different vehicleoperators. Such rearview mirrors are remotely controlled from inside thevehicle by a mechanical connection or an electrical connection.Electrically powered actuators are frequently included in rearviewmirror assemblies to reposition the mirror remotely in response toremotely controlled electrical signals. Such mirror assemblies areexpensive and require extensive labor for fabrication.

SUMMARY OF THE INVENTION AND ADVANTAGES

To achieve the goals of reducing complexity, expense and labor forfabrication, there is disclosed and described herein a rearview mirrorthat includes a shape memory alloy to effect the repositioning of amirror.

The rearview mirror includes a supporting assembly for attachment to avehicle structure and a mirror assembly with a pivot structure betweenthe assemblies for pivoting the mirror assembly relative to thesupporting assembly about first and second perpendicular intersectingaxes. A first electrically actuated moving mechanism pivots the mirrorassembly relative to the supporting assembly and is characterized byincluding a temperature sensitive element consisting of an alloy whichundergoes thermoelastic, martensitic phase transformation in response toheat and reacting between the assemblies for straining the elementduring a first phase and for unstraining the element during a secondphase. Also included is a supply of electrical power for heating theelement and causing the phase transformation of the element to unstrainthe elementing thereof to move the mirror assembly relative to thesupporting assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a fragmentary elevational view looking forwardly at the rearof a rearview mirror assembly which embodies the principles of thepresent invention with portions thereof broken away to show a pivotstructure;

FIG. 2 is a sectional view taken along the line 2—2 in FIG. 1 showing apower operated mirror moving mechanism in a first position;

FIG. 3 is a sectional view taken along the line 3—3 in FIG. 1 showing apower operated mirror moving mechanism in a second position;

FIG. 4 is an elevational view of a second embodiment of a rearviewmirror assembly showing a view similar to FIG. 1 with portions includinga pivot structure broken away to show a portion of a shape memory alloypower pack assembly;

FIG. 5 is a fragmentary elevational view looking rearwardly at the frontof the mirror assembly with portions thereof broken away to show theshape memory alloy power pack assembly;

FIG. 6 is a view similar to FIG. 5 showing a single strand membermounted in the power pack assembly;

FIG. 7 is a fragmentary cross-sectional view taken through the line 7—7in FIG. 5;

FIG. 8 is an isolated perspective view showing the power pack assembly,the pivot structure and a mirror unit; and

FIG. 9 is a view similar to FIG. 5 showing the power pack assembly in anactuated configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the Figures, wherein like numerals indicate like orcorresponding parts throughout the several views, there is shown inFIGS. 1-3 the preferred embodiment and best mode of a rearview mirrorassembly, generally designated 10, which embodies the principles of thepresent invention. The rearview mirror 10 includes a mirror assembly,generally designated 12 pivotally mounted within a supporting assembly,generally designated 14 by a pivot structure, generally designated 16.

The pivot structure 16 is secured to a support structure 18 shown inphantom in FIG. 1 which forms part of the supporting assembly 14. Thepivot structure 16 is generally disposed between the mirror assembly 12and the support structure 18 of the mirror support assembly 14 so thatthe mirror assembly 12 can be moved with respect to the supportingassembly 14 and held in an adjusted operating position by the pivotstructure 16. A shape memory alloy power pack assembly, generallydesignated 20, which includes a plurality of power operated mirrormoving mechanisms described and illustrated herein, is included in therearview mirror assembly 10 to provide powered adjustment of the mirrorassembly 12 with respect to the mirror support assembly 14.

The support structure 18 is made of a plastic or other suitable materialand is rigidly secured to a shell-like portion 23 of the mirror supportassembly 14 by a plurality of posts 25 in a conventional manner. Theshell-like structure 23 can be a plastic or other suitable material andforms the forwardly facing exterior of the rearview mirror assembly 10.The supporting assembly 14 is suitably fixed to an exterior side of amotor vehicle (not shown) as, for example, to the forward portion of aside door thereof.

The supporting assembly 14 can be of any conventional construction andneed not be a fixed support but could be a spring-biased manual orpowered fold-away support assembly of any known construction. Therearview mirror assembly 10 shown in the FIG. 1 is configured forinstallation on the left side of a vehicle where the left referencedirection is determined from the point of view of a forwardly facingvehicle occupant. It is understood, however, that the assembly 10 couldeasily be reconfigured for operation on the right side of a vehicle byconstructing a mirror image configuration of the rearview mirrorassembly 10.

The present invention is more particularly concerned with the manner inwhich the mirror assembly 12 is adjustably pivotally mounted to andmoved with respect to the support structure 18 by the shape memory alloypower pack assembly 20 than with the configuration and construction ofthe supporting assembly 14 and the attachment thereof to the vehicle orthe manner in which the support structure 18 is rigidly secured withinthe supporting assembly 14, all of which may be conventional.

The mirror assembly 12 generally includes a mirror 22 and a mirrorholder 24 within which the mirror 22 is mounted in fixed relation. Thepivot structure 16 includes a friction cup structure 26 integrallyformed with the mirror holder 24, a slip cup structure 28, a push nutspring structure 30 and a central post structure 32. A support cupstructure 33 on the support structure 18 frictionally engages andsupports the friction cup structure 26 in a manner described below.

The power operated mirror moving mechanisms of the shape memory alloypower pack assembly 20 are shown in FIG. 1 and include a first poweroperated mirror moving mechanism, generally designated 36, that isconstructed and arranged to selectively effect movement of the mirrorassembly 12 with respect to the supporting assembly 14 about a firstaxis of pivotal movement where the first axis is generally parallel tothe ground when the vehicle is parked on a level surface.

The power pack assembly 20 further includes a second power operatedmirror is constructed and arranged to selectively effect movement of themirror assembly 12 with respect to the supporting assembly 14 about asecond axis of pivotal movement where the second axis is generallyperpendicular to the ground when the vehicle is parked on a levelsurface and is generally perpendicular to the first axis.

The first power operated mirror moving mechanism 36 includes a firstpair of force applying structures 40 constructed and arranged to applyforces between the supporting assembly 14 and the mirror assembly 12 onopposite sides or ends of the first axis in contracting and extendingrelation therebetween.

The second power operated mirror moving mechanism 38 includes a secondpair of force applying structures 42 constructed and arranged to applyforces between the supporting assembly 14 and the mirror assembly 12 onopposite sides or ends of the second axis in contracting and extendingrelation therebetween.

In the preferred embodiment of the invention, the first and second pairsof force applying structures 40, 42 are each comprised of pairs ofessentially identical helical or coiled structures. The first pair ofhelical structures are designated 44 and 46 for reference and the secondpair of helical structures are designated 48 and 50 for reference. Eachhelical structure 44, 46, 48, 50 is comprised of a shape memory alloywire that has preferably been manufactured in the form of a coil spring.The preferred coil spring shape memory alloy wire is a nickel/titaniumalloy wire commercially available from the Raychem Corporation, theCorporate Headquarters of which is located at 300 Constitution Drive,Menlo Park, Calif. 94025-1164 and has a wire diameter of approximately0.4 mm, a free length when heated above the transition temperature ofapproximately 20 mm and a cold stretched length below the transitiontemperature of about 140 mm. These coil springs are operated between thelengths of about 140 mm to about 110 mm.

One skilled in the art will understand, however, that other shapedmemory alloy wires having similar characteristics can also be used. Anickel/titanium wire manufactured by and commercially available fromDynalloy Inc., 18622 MacArthur Blvd., Ste. 103, Irvine, Calif. 92715 andsold under the trademark Flexinol®, for example, can be shaped into acoil spring structure and used as a force applying structure in thepresent invention.

The general properties and characteristics of shape memory alloy wiresare well known to those skilled in the art. It is well known that shapememory alloy wire can be constructed to form a coil that shortens orcontracts when heated and lengthens and can be relatively easilystretched when cooled. More specifically, when heated through analloy-specific temperature range, shape memory alloys undergo a phasetransition from a martensitic phase to an austenitic phase in which thecoiled wire contracts to a memory position, reducing the height of thecoil and applying a significant pulling force as it contracts. Therearview mirror assembly 10 is constructed so that each coiled wire canbe individually heated by conducting an electrical current therethroughto effect the contracted memory position. When the current is switchedoff, the coil structure cools and can be easily stretched tomechanically transform the coil structure to a martensitic phase. Whenthe heat is no longer applied the helical structure acts as a normalcoil spring.

FIG. 1 shows that the helical structures 44, 46, 48, 50 arecircumferentially spaced about the pivot structure 16 at approximately90 degree angles and are equally spaced from the pivot structure 16.FIGS. 2-3 show the details of the mounting of the helical structures 44,46 in force applying relation between the mirror support assembly 14 andthe mirror assembly 12. FIGS. 2 and 3 are fragmentary cross-sectionalviews of the rearview mirror assembly 10 taken through the linedesignated 3,2—3,2 in FIG. 1 which coincides with the first axis. FIG. 2will be discussed first. FIG. 2 shows two of the helical structures 44,46 mounted between the support structure 18 and the mirror assembly 12in opposing force applying relation along the first axis to pivot themirror assembly 12 in opposite pivotal directions with respect to thepivot structure 16 and shows the pivot structure 16 in cross-sectionalview.

The pivot structure 16 includes the support cup structure 33 and thecentral post structure 32, both of which are integrally formed with thesupport structure 18. The friction cup structure 26 is integrally formedwith the mirror holder 24 portion of the mirror support assembly 14 andis slidably received within the support cup structure 33. The mirrorholder 24 can be plastic or other appropriate material.

The central post structure 32 extends through a central aperture S1 inthe friction cup structure 26; a middle aperture 53 on the push nutspring structure 30 is press-fit over the central post structure 32 tohold the friction cup structure 26 in frictional engagement between thesupport cup structure 33 and the slip cup structure 28.

More specifically, the friction cup structure 26 is held in an adjustedoperating position through the frictional engagement therewith by theslip cup structure 28 and the support cup structure 33. It can beappreciated from a comparison of the positions of the mirror assembly 12with respect to the mirror support assembly 14 in FIGS. 2-3 that thefriction cup structure 26 is slidably movable with respect to thesupport cup structure 33 and the slip cup structure 28. The slip cupstructure 28 does not move with respect to the push nut spring structure30 as the mirror assembly 12 is pivoted.

Frictionally engaged surfaces 55 and 57 of the support cup structure 33and friction cup structure 26, respectively, and frictionally engagedsurfaces 60 and 62 of the friction cup structure 26 and slip cupstructure 28, respectively, define sections of spherical surfaces tofacilitate omni-directional pivotal movement of the mirror assembly 12with respect to the support structure 18 about the pivot structure 16.

Although only the first pair 40 of force applying helical structure44,46 is shown in FIGS. 2-3, one skilled in the art will appreciate thatthe structure, mounting and operation of the second pair of forceapplying structures 42 is identical and the following discussion appliesequally to those structures. A first end 62 of each shape memory alloyhelical structure 44, 46 is secured to an anchor structure 64 on thesupport structure 18 of the mirror support assembly 14 and a second end66 of each helical structure 44, 46 is secured to an anchor structure 68on the mirror assembly 12.

The first end 62 of each helical structure 44, 46 is in electricalcommunication with a switch controlled automotive electrical powersource and the second end 66 thereof is in electrical communication withthe electrical system ground level voltage on the mirror assembly 12 sothat each helical structure 44, 46 can be supplied electrical powereither separately or in selected pairs to heat the same. Theseelectrical connections are conventional and are not shown in FIGS. 1-3to more clearly illustrate the invention.

Preferably the helical structures 44, 46 are mounted between the mirrorsupport assembly 14 and the mirror assembly 12 so that they exert atensile force therebetween in the martensitic or low temperature phase,regardless of the operating position of the mirror assembly 12. Thus,the helical structure 44, 46 would tend to move the mirror assembly 12and the mirror support assembly 14 toward one another.

When the helical structures 44, 46 are at normal operating temperatures,these combined spring forces exerted on the mirror assembly 12 areinsufficient alone or in combination to overcome the static frictionalforce of the pivot structure 16 so the mirror assembly 12 remainsstationary in all positions of adjustment.

FIGS. 2-3 show an example of what occurs when helical structure 44 isheated above the transition temperature thereof and contracts towardsits memory position to move the mirror assembly 12 in a first pivotaldirection along the first axis. FIG. 2 shows the first power operatedmirror moving mechanism 36 when the mirror assembly 12 is in a firstposition and each helical structure 44, 46 is in its martensitic ornonactuated phase.

When the helical structure 44 is heated with an electrical current, itcontracts toward its memory position and exerts a much higher force onthe mirror support assembly 14 than it does during its nonactuated, lowtemperature phase. The memory position of each structure 44, 46 is acoil structure having a height at least short enough to move the mirrorassembly 12 fully through its operational range in a given pivotaldirection. When the electrical current is switched on, the contractionbegins essentially instantaneously. This contractionary force issufficient to overcome the static frictional force holding the frictioncup structure 26 in the pivot structure 16 and the spring force of the-opposing helical structure 46 which is in its nonactuated phase andthereby effect the repositioning of the mirror.

FIG. 3 shows the mirror assembly 12 in a second adjusted operatingposition after the contracting helical structure 44 has moved the mirrorassembly 12 in the first pivotal direction about the first axis and theelectrical current has been cut off. The contraction stops immediatelyand the pivot structure 16 holds the mirror assembly 12 in the newposition.

A comparison of FIGS. 2-3 indicates that as the helical structure 44contracts, the opposing helical structure 46 moves and expands inresponse to the movement of the mirror assembly 12. This movement of theopposing helical structure 46 cools the shape memory alloy materialbecause during expansion each loop-like segment of the helix moves intoa region of cooler air. The cooling of the helical structure 46 duringthe expansion is particularly important if the helical structure 46 hasrecently been actuated and its temperature is elevated. Cooling helpstransform the alloy back to the martensitic phase. Each helicalstructure 44, 46 has a small diameter and cools essentiallyinstantaneously.

The transition temperature for the selected shape memory alloy materialis preferably high (it is preferably above 80 degrees Celsius and ispreferably about 90 degrees Celsius) so that when the electrical currentis cut off, the temperature differential between the heated helicalstructure 44 and the ambient atmosphere is high which facilitates rapidcooling.

The opposing helical structure 46 is stretched as it is moved throughthe air by the pivoting mirror assembly 12. This stretching of thehelical structure mechanically converts the shape memory, alloy thereinto the martensitic phase thereby decreasing the recovery time of thehelical structure 46 assuring that it can be reactuated essentiallyinstantaneously to move the mirror assembly 12 in the second pivotaldirection along the first axis.

Because of the rapid cooling of the helical structure 44 due to the hightemperature differential, the small wire diameter and the stretching ofthe helical structure 46 which reduces recovery time, the mirrorassembly 12 can be immediately repositioned in the second pivotaldirection along the first axis by heating the helical structure 46 andstretching the helical structure 44 after the current to the helicalstructure 44 has been switched off.

As aforesaid, in the preferred embodiment, the helical structures 44, 46are selected and mounted in force applying relation between the mirrorassembly 12 and the mirror support assembly 14 such that they exert atensile force therebetween in all adjusted operating positions of themirror assembly 12 in the martensitic phase. It is wlect and mounthelical structures 44, 46, 48, 50 that exert a compressionary force,i.e., a force that tends to move the mirror assembly 12 away from themirror support assembly 14 in all adjusted operating positions of themirror assembly 12 when the helical structures 44, 46, 48, 50 are intheir martensitic phase and to exert a strong tensile force between themirror assembly 12 and mirror support assembly 14 when actuated to theaustenitic phase.

It is further contemplated to select and mount the helical structures44, 46, 48, 50 such that they can exert either a compression or tensileforce therebetween, when the same are in their martensitic or lowtemperature phases, depending on the adjusted operating position of themirror assembly 12 with respect to the mirror support assembly 14. Thusit can be understood that in this configuration, each spring would passthrough a null position or zero force position in its martensitic phaseat some point within the operating range of adjustments of the mirrorassembly 12. Although one or more coils may be in the null position whenthe mirror assembly 12 is in a given operating position and may not beapplying a force, nevertheless for every other position of the mirrorassembly 12 the coils do apply a force and, hence, they are regarded inaccordance with the broadest aspects of the present invention to beforce applying structures.

It is also understood that in all embodiments, the mirror assembly 12 isrepositioned by the contraction of the selected helical structure orhelical structures in response to the heating thereof and that thetensile force generated by a helical structure in its austenitic orheated phase is much greater than the spring force, tensile orcompression, generated by the helical structures 44, 46, 48, 50 alone orin combination in their martensitic or low temperature phases.Consequently, the individual or combined spring forces of the helicalstructures 44, 46, 48, 50 in their martensitic phases does not elementof the mirror assembly 12 when the same is moved by an actuated helicalstructure and the individual or combined spring forces of the helicalstructures in their martensitic phases are sufficiently balanced thatthe mirror assembly 12 remains stationary until a helical structure 44,46, 48, 50 is contracted by heating in all positions of adjustment.

Adjacent pairs of helical structure 44, 46, 48, 50, as for examplestructures 44 and 48, can be simultaneously actuated to reposition themirror assembly 12 at the same time. It is contemplated that anappropriate switching mechanism be provided remote from the rearviewmirror assembly 10 in the interior of the vehicle proximate the leftside front seat that would allow actuation of any individual helicalstructure 44, 46, 48, 50 or simultaneous actuation of any adjacent pair,but would not allow simultaneous actuation of helical structures inopposing relationship, as for example, structures 44 and 46.

FIGS. 4-9 show an alternative embodiment of a rearview mirror assembly,generally designated 110. Identical structures between the twoembodiments 10 and 110 are given identical reference numbers and are notdescribed further.

FIG. 4 shows a view of the rearview mirror assembly 10 similar to theview of the rearview mirror assembly 10 shown in FIG. 1. In FIG. 4 somestructures have been removed including the pivot structure 16 and aportion of a housing structure 118 to show a portion of a shape memoryalloy power pack assembly, generally designated 134, which is generallydisposed within the housing structure 118.

The housing structure 118 is secured within and forms part of a mirrorsupport assembly, generally designated 114. A mirror assembly 112 ispivotally mounted on the housing structure 118 portion of the mirrorsupport assembly 114 by a pivot structure 16.

The power pack assembly 134 includes a first power operated mirrormoving mechanism generally designated 127 constructed and arranged toselectively move the mirror assembly 112 with respect to the mirrorsupport assembly 114 about a first axis that is essentially horizontalto the ground when the vehicle is parked in a level surface.

The power pack assembly 134 further includes a second power operatedmirror moving mechanism generally designated 129 constructed andarranged to selectively move the mirror assembly 112 with respect to themirror support assembly 114 about a second axis that is essentiallyvertical to the ground when the vehicle is parked in a level surface andis generally perpendicular to the first axis.

The first power operated mirror moving mechanism 127 includes a firstpair of force applying structures, generally designated 131, constructedand arranged to apply forces between the mirror assemblies 112, 114 onopposite sides of the first axis in contracting and extending relationtherebetween and the second power operated mirror moving mechanism 129includes a second pair of force applying structures, generallydesignated 133, constructed and arranged to apply forces between themirror assemblies 112, 114 on opposite sides of the second axis incontracting and extending relation therebetween.

The power pack assembly 134 is comprised of a cylindrical disk-shapedbase member 136 and a plurality of spring biasing assemblies 135. Aplurality of spring biased arm members 138, each of which forms part ofa spring biasing assembly 135, slidably mounted on the base member 136and a plurality of post members including an upper post member 140, alower post member 142 and first and second side post members 144 and145, respectively.

The upper, lower and side post members 140, 142, 144, 145 are eachrigidly secured within respective angular notches 146 formed at theperiphery of the base member 136. The post members 140, 142, 144, 145are essentially equally circumferentially spaced at the periphery of thebase member 136 so that they are approximately 90° (ninety degrees)apart and are positioned respectively at the top, bottom and sides ofthe base member 136 when the same is installed in the rearview mirrorassembly 10. Each post member 140, 142, 144, 145 is cylindrical anddefines a central annular groove thereabout, designated 143, 147, 148and 149, respectively. Each post member 140, 142, 144, 145 iscylindrical and the diameters thereof are unequal for reasons explainedhereinbelow.

The base member 136 is preferably made of a light weight electricallyconductive material such as aluminum, although a nonconductive materialsuch as plastic or a composite material could be used. Each springbiasing assembly 135 includes an arm member 138 and an associated pulley151, 152, 153, or 155. The post members 140, 142, 144, 145 arepreferably made of plastic or a composite material. Each post member140, 142, 144, 145 is provided with a reduced diameter cylindricalextension member (not shown) integrally and axially symmetrically formedat one end thereof, each of which is received within respective blindbores (not shown) formed in each notch 146. More specifically, eachperipheral edge portion of the base member 136 within each notch 146includes a bore that receives the respective extension member and theextension members are hd fastener members 150.

Each arm member 138 is provided with a pulley member designated 151,152, 153, 155 rotatably mounted thereon through which each arm member138 engages a force applying shape memory alloy strand member 154. Aswill become apparent, two opposing strand members 154 comprise the firstpair of force applying structure 131 and the other opposing pair ofstrand members 154 comprise the second pair of force applying structure133. Each pulley member 151, 152, 153, 155 is given a differentreference numeral because each is a different height, for reasonsexplained hereinbelow.

FIG. 5 shows an enlarged elevational view of the opposite side of thepower pack assembly 134 from that shown in FIG. 4. More specifically,FIG. 5 is a view of the rearview mirror assembly 110 seen when lookingrearwardly at the front of the supporting assembly 14; the supportingassembly 14 and the housing structure 118 are shown in fragmentary viewso that the power pack assembly 134 is illustrated.

A central block member 156 is secured to a central portion of the basemember 136 by threaded fasteners 158. Each spring biasing assembly 135includes an arm member 138 and an associated pulley 151, 152, 153 or155. Each arm member 138 includes an arm portion 159 slidably engagedwithin a groove structure 161 in the base member 136 and an outwardlyprotruding mounting block portion 160 integrally formed therewith at anend of the arm portion 159 opposite the pulley member 151, 152, 153,155. Each block portion 160 is slidably engaged with a rod structure162, each of which rod structures 162 is rigidly mounted to the centralblock member 156. A coil spring member 164 surrounds each rod structure162 and biases the respective arm member 138 radially outwardly alongthe groove structure 161. A pair of stop members 166 are secured inblocking relation over each groove structure 161 to limit the radiallyoutwardly sliding movement of each arm member 138 under the spring forceprber 164.

A plurality of identical lateral post members 168 are rigidly secured tothe base member 136 and are arranged thereon to form two radial tierswhich are comprised of an inner tier, generally designated 170 and anouter tier, generally designated 172. Each lateral post member 168 isgenerally cylindrical and includes a reduced diameter cylindricalextension member 74 integrally and axially symmetrically formed at oneend thereof. Each extension member 174 is secured within a bore 176 inthe base member 136 to secure the lateral post members 168 to the basemember 136. The extension members 174 and bores 176 are shown in FIG. 4.The inner tier 170 is comprised of six symmetrically andcircumferentially spaced lateral post members 168 and the outer tier iscomprised of eight symmetrically and circumferentially spaced lateralpost members 168. The base member 136 is secured to the housingstructure 118 through conventional threaded fasteners 177.

Four shape memory alloy strand members 154 are mounted on the power packassembly 134 in the following manner: a first end of each strand member154 is secured by a holder structure 178 which holder structure issecured to the base member 136 with conventional fasteners 180. It isunderstood that it is within the scope of the invention to secure thefirst end of each strand member 154 to any appropriate structure toanchor each strand member 154, including some portion of the mirrorsupport assembly 114 itself.

Generally, each strand member 154 is wound around a plurality of lateralpost members 168 in a spiral-like configuration and then around one ofthe pulley members 151, 152, 153, 155 of a respective spring biasingassembly 135 and then each strand member 154 engages one of the upper,lower or side post members 140, 142, 144, 145. The details of thismounting is shown in FIG. 6 which shows the mounting of a representativesingle strand member, designated 154 a. The other strand members 154 arenot shown so that this representative example can be better understood.It can be appreciated that the other three strand members 154 aremounted in a similar manner.

The representative strand member 154 a shown in FIG. 6 is secured at afirst end thereof between the holder structure 178 and the base member136. The holder structure 178 is held tightly to the base member 136 bythreaded fasteners 180 to hold the first end of the strand member 154 asecurely in place. The strand member 154 a is wound around the lateralpost members 168 starting with a proximate post member which is labeled168 a for reference. The strand member 154 a is then wound around aplurality of other lateral post members 168 in the inner tier 170thereof and then wound around the outer tier 172 lateral post members168.

The strand member 154 a engages pulley member 152 and then engages theannular groove 143 in the upper post member 140. The strand member 154 apasses though an appropriate aperture 182 in the housing structure 118and the second end of the strand member 154 a is secured to anessentially forwardly facing surface 184 of the mirror assembly 112 in amanner described hereinbelow. The post members 140, 142, 144, 145 and168 and the pulley members 151, 152, 153, 155 together comprise aplurality of spaced elements which cooperate to form a plurality ofelongated paths on the mirror support assembly 114 which support theshape memory alloy strand members 154 and direct the same to the mirrorassembly 112.

In the embodiment shown in the drawings there are eight lateral postmembers 168 in the outeeach arm member 138 is symmetrically between twoadjacent lateral post members 168 in the outer tier 172. The postmembers 140, 142, 144, 145 are, as described, essentially 90 degreesapart and the arm members 138 are also essentially 90 degrees apart fromeach other. The arm members are labeled 138 a, 138 b, 138 c and 138 d inFIG. 6 for reference. The arm member 138 a is approximately an equalradial distance from the two adjacent post members 140 and 145;similarly, the other arm members 138 b, 138 c and 138 d are essentiallyan equal radial distance from the adjacent post members 140 and 144; 144and 142; and 142 and 145, respectively.

In the embodiment shown in FIGS. 4-9, each strand member 154 spiralsoutwardly in a clockwise direction. As explained hereinbelow, each firstend of each shape memory alloy strand member 154 is in electricalcommunication with a switch controlled automotive electrical powersource and the second end thereof is in electrical communication withthe electrical system ground voltage level so that each strand member154 can be supplied electrical power either separately or in selectedpairs to effect the contraction of the selected strand member 154 orstrand members 154 to pivot the mirror assembly 112.

It can therefore be appreciated that the four strand members 154 areprovided to effect the pivotal movement of the mirror assembly 112 infour different pivotal directions. To this end, each strand member 154engages one pulley member 151, 152, 153 or 155 and then the upper, loweror side post member 140, 142, 144 or 145 that is immediately adjacentthereto in the clockwise direction. FIGS. 4-6 and 9 show that the upperand lower post member 140, 142 are vertical aligned so that therespective strand members 154 engaged therewith can be appropriatelysecured to the front surface 184 of the mirror assembly 112 in verticalalignment in proper position relative to the pivot structure 16 tocontrol the up or down pivotal movement of the mirror assembly 112.These two strand members 154 comprise the second pair of force applyingstructure 133. Similarly, the side post members 144, 145 and the strandmembers extending therefrom are approximately horizontally aligned tofacilitate the side to side pivotal movement of the mirror assembly 112.These two strand members 154 comprise the first pair of force applyingstructure 131.

Details of the mounting of the strand member 154 about the lateral postmembers 168 are shown in FIGS. 7-8. Each lateral post member 168 isprovided with four identical annular grooves generally designated 184,and designated 184 a through 184 d for reference in FIG. 7. Each pulleymember 151,152,153,155 is provided with a single annular groove186,187,189,191, respectively, to receive a single strand 154. Eachpulley member 151,152,153,155 is rotatably mounted on a respective armmember 138 by pin member 188,193,195,197.

It can be appreciated the strand member designated 154 a for referencein FIG. 7 is maintained in essentially a single plane parallel to thesurface 179 of the base member 136 as the strand member 154 a spiralsoutwardly toward the upper post member 140. This planar configuration ofthe spiraling strand member 154 a is achieved because the annular groove87 on the pulley member 152 and the annular groove 143 on the upper postmember 140 are both the same distance from the surface 179 as the firstgroove 184 a on each lateral post member 168.

Similarly, although only partially shown in FIG. 7, it can beappreciated that the groove 191 on pulley member 155 and the annulargroove 147 (not shown in FIG. 7) on the lower post member 142 are thesame distance from surface 179 as the fourth groove 184 d on eachlateral post member 168. It will be understood that the post members140, 142, 144, and 145 are unequal diameters and that the pulley members151,52,53,55 are unequal heights so that associated pairs thereofcorrespond in distance from surface 179 to one of the grooves 184 athrough 184 d on the lateral post members 168 to maintain the fourspiraling strand members 154 essentially parallel to each other and tosurface 179 of the base member 136. It will also be understood thatbecause each lateral post member 168 is provided with four separategroove structures, the spiral winding of the strand members 154 can beeffected without having two strand members 154 in the same annulargroove and that each strand member 154 can be maintained in anessentially planar confi.

One end of each rod structure 162 is rigidly secured within a blind bore192 in the central block member 156. Each rod structure 162 passesthrough an aperture 190 in the block portion 160 of the arm member 138associated therewith to effect the slidable mounting of each arm member138 on one of the rod structures 162.

The housing structure 118 is comprised of complimentary first 194 andsecond 196 housing members which are secured together by threadedfasteners (not shown) or by any conventional means. The housingstructure 118 is secured with threaded fasteners (not shown) or by otherconventional means to a plurality of legs structures 198, 200 integrallyformed on the supporting assembly 14. The second housing member 196 isprovided with enlarged portions 111 and 113, respectively, toaccommodate the post members 140 and 144. Enlarged portions (not shown)are provided for post members 142 and 145.

The pivot structure 16 is shown in the cross-sectional view of FIG. 7.The structure the pivot structure 16 is essentially the same in bothembodiments 10, 110 so a discussion of the structure will not berepeated in detail. The support cup structure 33 and the central poststructure 32 are both of which are integrally formed with the secondhousing member 196, but this is not considered a major difference inconstruction.

It can be appreciated from the phantom representation of the pivotedmirror unit in FIG. 7 that the pivot structure 16 friction cup structure26 is slidably movable with respect to the support cup structure 33 andthe slip cup structure 28.

The second end of each strand member 154 is provided with an enlargedmember 208 which facilitates the attachment of the respective strandmember 154 to an integral attachment structure 217 on the holder member124. The enlarged member 208 can be a hollow cylindrical structure madeof a soft metal that is crimped around the strand member 154. As bestseen in FIG. 8, the integral attachment structure 217 includes a sideopening 219 which receives the strand 154 and the enlarged member 208and a top aperture 221. The top aperture 221 has a large enough diameterto allow the strand member 154 to pass therethrough but is small enoughto prevent the enlarged member 208 from passing therethrough so that thestrand member 154 is secured to the mirror assembly 112. The second endof each strand member 154 is in electrical communication with aconductive structure 209 within the mirror assembly 112 which is in turnin electrical communication with terminal member 210 which are connectedthrough a wire member (not shown) to ground voltage of the vehicle.

It can be appreciated from FIG. 8 that respective second ends of thestrand members 154, two of which are shown in phantom, one of which isshown in solid lines and one of which is not visible, arecircumferentially spaced around the pivot structure 16 essentiallyninety degrees apart and are positioned to move the mirror assembly 112upwardly, downwardly and side-to-side. FIG. 8 shows the power packassembly 134 with only one strand member, designated 154 a, mountedtherein. The other three are not shown to more clearly illustrate theinvention.

It is well known that strand members 154 that contain a shape memoryalloy can be constructed so that each strand member 154 independentlyshortens when heated and lengthens or can be relatively easily stretchedwhen cooled. More specifically, when heated through an alloy-specifictemperature range, shape memory alloys undergo a phase transition from amartensitic phase to an austenitic phase in which the strand member 154effects a contracted or memory position. Each strand member 154 can beindividually heated by placing an electrical current therethrough toeffect the contracted memory position. When the current is switched off,the strand member 154 cools and can be easily stretched to mechanicallytransform the strand members 154 to a martensitic phase.

The preferred shape memory alloy for the strand members 154 is anickel/titanium allow commercially available from Dynalloy, Inc. 18622MacArthur Blvd., Ste 103, Irvine, Calif. 92715 and sold under thetrademark Flexinol®. More specifically, the preferred Flexinol® wire hasa 0.015 inch diameter and is rated to have a transition temperature of90 degrees Celsius. It will be understood that other shape memory alloywires can be used such as comparable shape memory alloy wirescommercially available from Raychem, Inc. and sold under the trademarkNitinol®. The address of Raychem, Inc. is set forth above.

The operation of the power pack assembly 134 can be appreciated byexamining FIG. 9. Identical structures are given different letterdesignations for purposes of illustration. FIG. 9 shows an actuatedconfiguration of the power pack assembly 134 realized when one of thestrand members is heated by passing a current therethrough to repositionthe mirror assembly 112. The energized strand member is designated 154 ain FIG. 9 for reference. It can be appreciated that this strand member154 a engages the upper post member 140 and extends rearwardly therefromfor attachment to an upper portion of the forwardly facing surface 184of the mirror assembly 112 and is attached above the pivot structure 16to upwardly pivot the mirror assembly 112. It can also be appreciatedthat the strand member designated 154 c is in opposing relationship tostrand member 154 a and is secured to the surface to structure todownwardly pivot the mirror unit when contracted. Strand members 154 aand 154 c are also shown and labeled in FIG. 9.

When strand member 154 a is heated, it shortens toward its memoryposition. This causes the arm member of the spring biasing assembly 135associated therewith, designated 138 a for reference, to slide radiallyinwardly to a fully contacted position. The fully contracted position isrealized when the associated spring member 164 a is fully compressed.After arm member 138 a is fully contracted, further shortening of thestrand member 154 a causes the mirror assembly 112 to pivot upwardlyabout the pivot structure 16. More specifically, further shortening ofthe strand member 154 a after the arm member 138 a is fully contractedcauses the friction cup structure 26 to slide with respect to both thesupport cup structure 33 and the slip cup structure 28.

As the mirror assembly 112 pivots, the pivoting motion of the mirrorunit simultaneously stretches the opposing strand member 154 c and atleast partially contracts the arm member 138 c associated therewithwhich compresses the spring member 164 c associated therewith. When themirror assembly 112 reaches the desired adjusted operating position, thestrand member 154 a is de-energized causing it to stop contracting. Thepivot structure 16 holds the mirror assembly 112 in the new adjustedoperating position.

After the mirror assembly 112 is in the desired adjusted operatingposition and the power is turned off, the compressed spring members 164of the spring biasing members 135 stretch the strand members 154associated therewith. In general, the spring force provided by thespring members 164 is great enough to stretch the strand members 154when the strand members 154 are below their highest martensitetransition temperature (sometimes referred to as the martensiteinitiation temperature), but not great enough to stretch a strand member154 in the austenite phase. Furthermore, it can be appreciated that thespring force provided by a single coil spring members 164 (or by twoadjacent coil spring members 164 if two adjacent strand members 154 areactuated simultaneously to reposition the mirror unit) is not greatenough to cause the displacement of the friction cup structure 26 withrespect to the support cup structure 33 and the slip cup structure 28.Therefore, when the actuated strand member 154, in the example abovestrand member 154 a, is de-energized, the mirror assembly 112 does notpivot any farther and the compressed coil spring members 164 function tostretch both the strand members 154 a, 154 c to mechanically induce themartensite phase therein. It is understood that the actuated strandmember 154 a does not begin to stretch under this spring bias forceuntil it has sufficiently cooled to enter the martensite phase, but thiscooling is typically realized essentially instantaneously. The armmembers 138 a and 138 c of the spring biasing assembly 135 slideradially outwardly until they contact the respective stop members 166associated therewith. When this point is reached, the strand members 154are in the martensite phase and either can be contracted when energized.

It is also understood that the strand members 154 would undergo thisphase transition from austenite to martensite without the presence ofthe spring members 164, but this transition is facilitated by the springforce applied by these spring members 164 on the strand members 154.Hence, the spring members decrease the recovery time for the strandmembers which have been heated to contract the same. The arm members 138hold the strand members 154 taut when they are in the non-energizedstate to maintain the strand members 154 within the grooves 184 on thelateral post members 168. Each strand member 154 therefore applies aforce to the mirror assembly 112 when the strand members 154 are intheir martensitic phase, and the mirror assembly 112 is stationary, butthese forces are sufficiently balanced that the mirror assembly 112remains stationary with respect to the mirror support assembly 14. Thestrand members 154 b, 154 d are similarly in opposing relationship andare independently energizable to contract either of the same toselectively reposition the mirror assembly 112 from side to side.

Adjacent pairs of strand members 154, as for example the strand membersdesignated 154 a and 154 b in FIG. 7, can be simultaneously actuated toreposition the mirror assembly 112 at the same time. It is contemplatedthat an appropriate switching mechanism may be provided remote from therearview mirror assembly 10 in the interior of the vehicle proximate theleft side-front seat that would allow actuation of any individual strandmember 154 or simultaneous actuation of any pair of adjacent strandmembers 154, but would not allow simultaneous actuation of strandmembers 154 in opposing relationship, as for example, strand members 154a and 154 c.

It is understood that the foregoing embodiments are exemplary only andnot intended to be limiting. One skilled in the are will appreciate, forexample, that even though each the strand members 154 shown in thesecond embodiment is comprised entirely of shape memory alloy materialthroughout its length, this is not a requirement. A portion or portionsof each strand member 154 can be comprised of a shape memory alloy andother portion or portions can be made of any suitable material,including any conductive material.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation.

Many modifications and variations of the present invention are possiblein light of the above teachings and the invention may be practicedotherwise than as specifically described within the scope of theappended claims.

What is claimed is:
 1. A rearview mirror for a vehicle comprising: asupporting assembly for attachment to a vehicle structure; a mirrorassembly; a pivot structure between said assemblies for pivoting saidmirror assembly relative to said supporting assembly about first andsecond perpendicular and intersecting axes; a first electricallyactuated moving mechanism disposed to selectively effect movement ofsaid mirror assembly with respect to said supporting assembly about saidfirst axis; a second electrically actuated moving mechanism disposed toselectively effect movement of said mirror assembly with respect to saidsupporting assembly about said second axis; characterized by including atemperature sensitive element consisting of an alloy which undergoesthermoelastic, martensitic phase transformation in response to heat andreacting between said assemblies for straining said element during afirst phase and for unstraining said element during a second phase, andin response to a supply of electrical power said element is actuatedcausing said phase transformation of said element to unstrain saidelement extracting energy from said element during said unstrainingthereof to move said mirror assembly relative to said supportingassembly.
 2. A mirror as set forth in claim 1 wherein said firstmechanism includes a first pair of said elements to apply forces betweensaid assemblies on opposite sides of said first axis, and said secondmechanism includes a second pair of said elements to apply forcesbetween said assemblies on opposite sides of said second axis.
 3. Amirror as set forth in claim 2 wherein said first pair of elements arebalanced for normally maintaining said mirror assembly stationary aboutsaid first axis in relation to said supporting assembly, and whereinsaid second pair of elements are balanced for maintaining said mirrorassembly stationary about said second axis in relation to saidsupporting assembly.
 4. A mirror as set forth in claim 3 wherein each ofsaid elements contracts in response to heat to extract energy duringsaid unstraining thereof.
 5. A mirror as set forth in claim 4 whereineach of said elements heats in response to electrical current passingthrough said element.
 6. A mirror as set defined in claim 2 wherein eachof said elements comprises a wire of shape memory alloy preformed into ahelical coil configuration, each helical coil wire having ends connectedbetween said assemblies.
 7. A mirror as set defined in claim 2 whereinsaid shape memory alloy has a transition temperature of 90° Celsius. 8.A mirror as set forth in claim 2 wherein each of said elements comprisesa wire of shape memory alloy, each shape memory wire having one endthereof fixed to said mirror assembly and having a substantial lengthextending to said supporting assembly, each substantial length of shapememory alloy wire being held by spaced elements in an elongated path onsaid supporting assembly leading from an end thereof fixed to saidsupporting assembly to said mirror assembly.
 9. A mirror as set forth inclaim 8 wherein each substantial length of shape memory alloy wire istensioned along its path by a spring biasing assembly.
 10. A mirror asset forth in claim 9 wherein said shape memory alloy wire has atransition temperature of 90° Celsius.